Vibrating throat platework feeding mechanisms



Sept. 16, 1969 w. c. VAN NESS 3,467,033

VIBRATING THROAT PLATEWORK FEEDING MECHANISMS Filed Nov. 20, 1967 Fig.4 William C. Van Ness United States Patent O 3,467,038 VIBRATING THROAT PLATEWORK FEEDING MECHANISMS William C. Van Ness, Parsippany, NJ., assignor to The Singer Company, New York, N.Y., a corporation of New Jersey Filed Nov. 20, 1967, Ser. No. 684,281 Int. Cl. Db 27/02 US. Cl. 112-203 4 Claims ABSTRACT OF THE DISCLOSURE A work feeding mechanism for a sewing machine is disclosed in which a work feeding element is sustained at substantially constant elevation relatively to the sewing machine work supporting bed and moved in the line of feed. The sewing machine throat plate while being maintained substantially parallel to the sewing machine work supporting bed is alternatively raised above the level of the work feeding element and lowered beneath the level of the work feeding element.

BACKGROUND OF THE INVENTION Conventional four-motion work feeding mechanisms for sewing machines provide a feed dog which is movable vertically into and out of engagement with work fabrics through slots in a stationary throat plate on the sewing machine bed. The conventional four-motion work feeding mechanism also imparts a feed stroke to the feed dog while it is raised above the throat plate, and a return stroke while the feed dog is lowered.

In addition to the complexity of actuating mechanism required to impart both vertical and horizontal movements to a feed dog, a conventional four-motion work feeding mechanism raises the feed dog in opposition to the sewing machine presser foot at the beginning of the work feeding stroke. Inertia forces acting on the presser device, therefore, can cause overthrow of the rising movement of the presser foot, thus diminishing the effectiveness of the work feeding mechanism.

Various work feeding mechanisms for sewing machines have been provided heretofore in which the feed dog is supported at a constant elevation. The simplest of these prior mechanisms leaves the feed dog constantly in engagement with the work fabric and relies upon the inclination of the teeth of the feed dog to feed the work only on movement of the feed dog in one direction of reciprocation. This type of work feed mechanism will mark or damage delicate fabrics. Mechanisms are also known in which the work support or throat plate is pivotally supported and actuated so as to swing up to a level above a constant level of the feed dog during the return stroke of the feed dog. By pivoting the throat plate, these known mechanisms introduce an angular variation of the throat plate relatively to the feed dog so that either the front or the rear of the feed dog first engages the work fabric and as a result an unevenness of feed is experienced.

SUMMARY OF THE INVENTION It is an object of this invention to provide a work feeding mechanism for a sewing machine in which a work feeding element remains at substantially constant level and is moved in the direction which the work is to be fed and in which a throat plate through which the work feeding element can project is maintained constantly parallel to the constant level of the work feeding element and is raised and lowered in timed relatio to the feed alternately to expose and cover the work feeding element.

With this construction, since the presser foot is ele- 3,467,038 Patented Sept. 16, 1969 vated out of opposition to the work feeding element by the rising of the throat plate during this period of ineffectiveness of the work feeding element, overthrow due to inertia forces in the raising of the presser foot will not give rise to undesirable feeding characteristics. Moreover, since the throat plate remains parallel to the level of the work feeding element, the work feeding element will always project equally at front and rear through the throat plate slots, thus providing an advantageous evenness of the work feed.

DESCRIPTION OF THE DRAWINGS With the above and additional objects and advantages in View, as will hereinafter appear, this invention comprises the devices, combinations and arrangements of parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which:

FIG. 1 represents a transverse cross sectional view of a sewing machine bed including a fragment of the presser device and having the work feeding mechanism of this invention applied thereto, 7

FIG. 2 is a bottom plan view of the work feeding mechanism of FIG. 1,

FIG. 3 is a cross sectional vew taken along line 3--3 of FIG. 1,

FIG. 4 is a cross sectional view taken substantially along line 44 of FIG. 2, and

FIG. 5 is a diagrammatic perspective view of the work feeding mechanism of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT As illustrated in the drawing, 11 indicates a sewing machine bed having a work supporting top 12 and webs 13, 14 and 15 formed beneath the work supporting top. Journaled in the bed is a feed advance rock shaft 16 arid feed lift rock shaft 17. The feed actuating rock shafts 16 and 17 may be conventional in every respect including the means in which they are suspended in the bed on tapered pintles such as pintle 18 threaded in the web 14 and engaging the feed lift rock shaft 17, and the pintle 19 which is carried in the web 13 engages the feed advance rock shaft 16. It will be understood that opposing pintles (not shown) carried in the bed engage the oppo site extremities of the rock shafts 16 and 17.

Freely rotatable on the feed lift rock shaft 17 is an eccentric sleeve 21 formed with a serrated flange 22. The eccentric sleeve is constrained lengthwise along the rock shaft between collars 23 and 24 which are fixed to the rock shaft by set screws 25. A guide bracket 26 having a guideway 27 is formed with a split hub 28 which embraces the eccentric sleeve 21 and may be secured to the sleeve by means of a clamp screw 29. The guideway 27 slidably accommodates one extremity 31 of a feed bar 32 which at the other extremity is pivoted on the pin 33 carried by the spaced rock arms 34 extending upwardly from the feed advance rock shaft 16. Secured to the feed bar as by screws 35 is a feed dog 36 formed with work engaging surfaces which may take the form of one or more rows of teeth 37 as illustrated in the drawing, or may be of other known forms such as resilient pads or the like.

The work engaging surfaces 37 of the feed dog 36 as illustrated in FIG. 1 are arranged in an aperture 38 in the work supporting top 12 of the bed and are opposed by the presser device of the sewing machine which, as illustrated in FIG. 1, may take the form of a conventional presser foot 39.

By virtue of the above described supporting means for the feed bar, the work engaging surfaces 37 of the feed dog may be constrained to move in a substantially fixed plane relatively to the sewing machine bed. By loosening the clamp screw 29 and turning the eccentric sleeve 21 the substantially fixed plane in which the feed dog work supporting surfaces can move may be adjusted vertically relatively to the work supporting top 12 of the sewing machine bed. Oscillation of the feed advance rock shaft 16, as by operation of any conventional feed drive means, will impart linear reciprocatory movement to the feed dog, while oscillation of the feed lift rock shaft 17 will have no influence on the feed dog motion.

Located with slight clearance within the aperture 38 of the work supporting top of the sewing machine bed is a throat plate 41 which is formed with slots 42 accommodating the feed dog teeth 37. The throat plate 41 is secured by screws 43 to the supporting frame 44. One arm 45 of the frame is pivoted by a pin 46 to a horizontal rock arm 47 of which the split hub 48 is secured to the feed lift rock shaft 17 as by a clamp screw 49. The other arm 51 of the throat plate supporting frame 44 is pivoted by a pin 52 to a vertical link 53 which in turn is pivoted on a pin 54 to the horizontal arm 55 of a lever 56 of which the hub 57 is pivotally supported on a t fulcrum screw 58 secured in the web 15 of the sewing machine bed. A vertical rock arm 61 having a split hub 62 secured on the feed lift rock shaft 17 by a clamp screw 62 is pivotally connected by a pin 64 to a connecting link 65 which is pivotally connected in turn by a pin 66 to the lever 56 vertically beneath the fulcrum screw 58.

Oscillation of the feed lift rock shaft 17 as by any conventional sewing machine feed actuation mechanism will thus impart substantially vertical reciprocating motion to the one arm 45 of the throat plate supporting frame by way of the horizontal rock arm 47 and simultaneously by way of the vertical rock arm 61, the connecting link 65, the horizontal arm 55 of the lever 56, and the vertical link 53 will impart similar substantially vertical reciprocating motion to the other arm 51 of the throat plate supporting frame 44. The throat plate 41, therefore, will be constrained constantly perpendicular to the fixed plane of the feed dog work engaging surfaces 37, and the throat plate will reciprocate alternately between positions above and below the level of said fixed plane. The vertical link 53 will accommodate any slight variation in the tolerances of the dimensions of the throat plate supporting parts.

The horizontal rock arm 45 and the horizontal lever arm 55 are each offset a substantially equal amount laterally from their respective centers of oscillation so that translatory movement of the throat plate will result.

Any known device and control arrangement for the feed advance and feed lift rock shafts 16 and 17 may be employed such as have been used heretofore to drive four motion feed mechanisms i.e., in which the feed dog is shifted vertically as well as horizontally. The United States Patent No. 2,330,177, of J. D. Karle, Sept. 21, 1943, is representative of this type of drive and control arrangement. It will be apparent that the feed advance and feed lift rock shafts are to be oscillated in timed relationship so that the throat plate 41 will be lowered beneath the fixed plane of the feed dog teeth 37 while the feed dog is being reciprocated in a feed stroke and the throat plate 41 will be reciprocated above the level of the fixed plane containing the feed dog teeth 37 while the feed dog is reciprocated in a return stroke.

The mechanism of the present invention is advantageous as compared with the conventional four-motion work feeding mechanism in that by moving the work feeding ele- .4 ment and the throat plate individually in mutually perpendicular directions, a more perfectly square motion of the work feeding element relatively to the throat plate is attained with the resulting high degree of evenness of work feed. It will be appreciated that the advantages provided by this invention will be obtained regardless of the type of Work feeding element which is used so that in addition to a reciprocated feed dog as described in the preferred embodiment other work feeding elements such as feed Wheels, feed belts and the like may be used.

Having thus set forth the nature of this invention, what is claimed herein is:

1. A work feeding mechanism for a sewing machine comprising a work feeding element having work engaging surfaces, means supporting said work feeding element for movement of said work engaging surfaces in a substantially fixed plane relatively to the said sewing machines, actuating means for reciprocating said work feeding element, a throat plate having clearance opening accommodating said feeding element work engaging surfaces, means for sustaining said throat plate substantially parallel to the fixed plane of said feeding element work engaging surfaces, and actuating means for reciprocating said throat plate in a direction perpendicular to the fixed plane of said feeding element work engaging surfaces into positions alternately above and below the level of said fixed plane in such timed relation to the reciprocation of said work feeding element that said throat plate is below the level of said fixed plane during the feeding movement reciprocation of said work feeding element.

2. A work feeding mechanism as set forth in claim 1 in which said work feeding element comprises a feed dog.

3. A work feeding mechanism as set forth in claim 1 in which said means for sustaining said throat plate substantially parallel to the fixed plane of said feed element work engaging surfaces comprises a frame secured to said throat plate and formed with spaced arms extending one on each side of .said throat plate, a pair of levers pivotally mounted in said sewing machine, means connecting each of said pair of levers with a respective one of said frame arms, and means for oscillating said levers in synchronism to impart translatory movement to said throat plate.

4. A work feeding mechanism as set forth in claim 3 in which said means connecting one of said pair of levers with a respective one of said frame arms includes a pivoted link, said link being arranged substantially mrpendicular to said fixed plane of said feed element Work engaging surfaces.

Refereuces Cited UNITED STATES PATENTS 1,432,084 10/ 1922 Nielsen 112203 1,526,937 2/ 1925 Sharaf 112-203 2,197,255 4/ 1940 Kucera 112214 2,330,177 9/1943 Karle l12215 2,892,427 6/1959 Winberg 112-203 X FOREIGN PATENTS 544,068 6/1956 Italy.

ALFRED R. GUEST, Primary Examiner US. Cl. X.R. 112215 

